1. Field of the Invention
This invention is related to the field of protecting digital information from being copied, modified, or used by unauthorized parties. In particular this invention is related to systems and methods that prevent unauthorized access to, and modification of, digital data as found on computer systems and consumer-appliance systems that utilize Compact Disc (CD), DVD, or other removable media (such as Flash Memory on standard or proprietary cards or sticks, or other non-volatile memory) technologies.
2. Description of the Related Art
The electronic publishing industry for application software, computer games, appliance-console games, movies, and music, is facing a growing and serious problem; namely, the piracy and unauthorized modification and use of their content. Since digital content is by nature capable of being copied exactly, wherein a copy is identical in every way to the original, and since the tools to do so are increasingly available, the industry is facing increasing losses. Such losses may include the unauthorized copying of a CD containing a game, or the unauthorized reverse engineering and modification of a word processing program to allow for its illegal distribution, or the reverse engineering of a copy protection scheme to disable it, making it possible to make duplicates with ease.
There are many mechanisms available that may be used to limit or prevent unauthorized access to digital content. Following deployment, such mechanisms are often times subsequently compromised by hackers, and the methods and techniques used to compromise them have been widely disseminated and actively used and enhanced. Most protections are simplistic in nature, and depend to large degree on the secrecy of the simple method as much as its inherent security or ingenuity, such that if not defeated prior to publication, the act of publishing them, for example in patent form, reveals enough about them to render them less effective. More than one of these approaches may be defeated if anticipated by using “ProcDump”, a memory lifting tool that is available free on the World Wide Web (such a tool may also be easily written following technical instructions that may also be found on the web) in conjunction with SoftICE, a powerful debugging tool, which may also be found on the web. A computer system is usually the platform and tool of choice for one intent on reverse engineering or cracking these protection mechanisms; even if the protected content's target was not a computer system such as a PC but rather an appliance computing device such as a game console, the content can best be modified (“hacked”) on a computer. In terms of protecting content from copying or modification by a skilled person with a modern computer system, most inventions in the field (see below) are not protected from being reverse engineered, modified, or content-duplicated by means of commonly available tools such as “SoftICE” (an in-circuit emulator and very powerful debugger), “ProcDump” (can capture any data content from any memory location, regardless of how protected the memory was thought to be), “IDA” (a disassembler), and “FileMon” (a file system monitoring and transcribing service tool). There are no design secrets that can be kept from such a set of tools, and there are many more such tools in existence, and more being created all the time. Therefore it becomes far more important to have well designed mechanisms that do not depend on their secrecy, as much as their design, to ensure security.
A number of patent references describe a variety of methods for protection of digital data and content. These include the following U.S. Pat. Nos. 4,405,829, 4,864,616, 4,888,800, 4,999,806, 5,021,997, 5,027,396, 5,033,084, 5,081,675, 5,155,847, 5,166,886, 5,191,611, 5,220,606, 5,222,133, 5,313,521, 5,325,433, 5,327,563, 5,337,357, 5,351,293, 5,341,429, 5,351,297, 5,361,359, 5,379,433, 5,392,351, 5,394,469, 5,414,850, 5,473,687, 5,490,216, 5,497,423, 5,509,074, 5,511,123, 5,524,072, 5,532,920, 5,555,304, 5,557,346, 5,557,675, 5,592,549, 5,615,264, 5,625,692, 5,638,445, 6,052,780 and 6,185,686.
Many of the aforementioned mechanisms depend to a great extent on lack of knowledge about the mechanisms by the persons attempting to modify or copy the content. With even partial knowledge, many of these mechanisms can be defeated by even a moderately technical person with access to the web where all the necessary tools and techniques are available. There is a need for security methods that do not depend solely upon their secrecy or obscurity in order to be effective.